This application claims the priority of Japanese Patent Application No. 2001-259838 filed on Aug. 29, 2001, which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a measuring apparatus, and more particularly to a protecting mechanism which can surely prevent the collision of a moving member thereof.
2. Description of the Related Art
Conventionally, a measuring apparatus such as an image measuring apparatus for measuring the image of a measuring surface of a workpiece has often been used.
The image measuring apparatus comprises an image device for measuring the image of the scene on the measuring surface of a workpiece, a moving device for moving the image device, and a controller such as a driving circuit for controlling the operation of the moving device. The image device includes a CCD camera and a moving member such as an objective lens, and the moving member such as an objective lens is moved by the moving device in such a direction as to separate from or approach the measuring surface of the workpiece. The moving device is caused to move the objective lens by means of the controller in such a manner that the measuring surface of the workpiece is placed in the focal position of the objective lens, and the scene of the measuring surface of the workpiece or the like is measured by the image device.
In the measuring apparatus described above, for example, it is very important that the moving member such as an objective lens does not come in contact with an object such as a workpiece or a jig.
In the measuring apparatus described above, however, the moving member such as an objective lens is caused to collide with an object such as a workpiece, a jig or a measuring apparatus body due to a careless manipulation, the mistake of a part program or the like, for example. Consequently, there is a possibility that the workpiece, the objective lens, the measuring apparatus body or the like might be damaged, for example.
Then, it can be proposed that a protector for preventing the collision of the moving member described above is provided in the measuring apparatus.
However, a recent measuring apparatus hardly has an empty space due to a reduction in a size and space saving, and furthermore, an excessive empty space is hardly provided due to the installation of accessories or the like.
For this reason, conventionally, it is actually hard to newly provide a general large-scaled protector on the recent measuring apparatus and the development of any countermeasure for the prevention of a collision against the moving member has been required urgently.
The present invention has been made in consideration of the problems of the prior art and has an object to provide a measuring apparatus which can surely prevent the collision of a moving member.
In order to attain the object, the present invention provides a measuring apparatus comprising a moving member which is moved to obtain information about a workpiece and might collide with a certain object, a moving device for moving the moving member, and a protector for preventing the moving member from colliding with the object. The protector is characterized by a protector body, a sensor, a strain detector, and a controller.
The protector body is provided in a portion of the moving member in which a collision with the object is to be avoided.
Moreover, the sensor is protruded from the protector body by a predetermined length to come in contact such that a distance between the object and the protector body has a predetermined value or less, and is elastically deformed by a contact with the object.
The strain detector detects the amount of the elastic deformation of the sensor.
The controller stops the movement of the moving member by the moving device or sets the same movement in a reverse direction when the amount of the elastic deformation detected by the strain detector exceeds a predetermined amount.
Herein, the object has a possibility that the moving member might collide therewith, and optionally includes a workpiece and a measuring apparatus body, and furthermore, a jig present in the moving range of the moving member, a user and the like, for example.
Moreover, the information about the workpiece includes the shape, length, angle and scene of the measuring surface of the workpiece and the like, for example.
Examples of the strain detector according to the present invention include a strain gauge, piezo-electric element and the like.
In the present invention, there is provided an image device including an objective lens as the moving member and serving to measure the image of the measuring surface of the workpiece through the objective lens. The moving device moves at least the objective lens of the image device in a direction of an optical axis thereof. The controller moves at least the objective lens by the moving device such that the measuring surface of the workpiece is placed in a focal position of the objective lens. It is preferable that the sensor should be shorter than the focal length of the objective lens and should have such a predetermined length as to be protruded from a tip of the objective lens.
Herein, the movement of at least the objective lens in the direction of the optical axis includes the movement of the objective lens in the image device in the direction of the optical axis, and furthermore, movement in a direction other than the optical axis, for example, a direction orthogonal to the direction of the optical axis.
Furthermore, the movement of the objective lens includes the movement of the objective lens together with CCD camera in addition to the case in which only the objective lens is substantially moved.
In the present invention, moreover, it is also preferable that the sensor should include a plurality of projection members provided apart from each other along an outer periphery of the objective lens.
In the present invention, furthermore, the strain detector should be provided in the protector body in a close to or contact with a base portion of the sensor. Moreover, it is preferable that a cut portion is provided in the protector body such that an elastic deformation of the sensor which is caused by a collision of the sensor and the object elastically deforms the protector body and an amount of the elastic deformation of the protector body corresponding to an amount of the elastic deformation of the sensor is detected by the strain detector.
In the present invention, moreover, it is also preferable that the sensor should include a ring-shaped member provided in a suspending condition from an end of the projection member.
Herein, the ring-shaped member includes a continuous ring-shaped member, a ring-shaped member provided with a plurality of cut portions in the ring-shaped member and divided into a plurality of parts by the cut portions and the like.
In the present invention, furthermore, it is preferable that the sensor should have a tip portion bulged outward from a side surface portion of the moving member or a side surface portion of the protector body with a longitudinal direction thereof turned obliquely to a direction of movement of the moving member.
In the present invention, moreover, it is preferable that the sensor should be constituted to be plate-shaped and the strain detector should be provided in a base side surface portion of the plate-shaped sensor in which an elastic deformation is generated by a collision of a tip portion of the plate-shaped sensor and the object.
In the present invention, furthermore, it is preferable that the plated-shaped sensor should be constituted by a material which is greatly deformed elastically by a collision with the object. Examples of a material which is greatly deformed elastically by the collision with the object includes a resin such as polypropylene.